Not exactly a mistake fare, but a pretty good fare that I thought was worth posting briefly about. Lima seems to be a popular destination these days and while using points/miles is generally a good value to South America (because most award chart devaluations spared this region), this cash price will be enticing for some.
The cheapest fares I’ve seen are out of Toronto (YYZ) on Delta for $1,073 round trip, but United also has decent rates if you’d rather fly and earn miles with them. Economy tickets will run you about $715-$800 for similar dates, so a premium of $400 is a pretty good deal to get into Business Class in my opinion. I like booking on Priceline.com, but you can book from your favorite website. Note that my searches below were done on ITA Matrix.
Fares are also valid from numerous other cities throughout North America, including Vancouver, Seattle, Los Angeles, New York (JFK and LGA), and others. Note that the Economy price is different for each city, so be sure to check both if you’re trying to decide if it’s worth it to fly in Business Class.